<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>重复网格</title>
</head>
<body>
  <canvas width="512" height="512"></canvas>
  <script src="./lib/gl-renderer.js"></script>
  <script>
    const vertex = `
      attribute vec2 a_vertexPosition;
      attribute vec2 uv;

      varying vec2 vUv;

      void main() {
        gl_PointSize = 1.0;
        vUv = uv;
        gl_Position = vec4(a_vertexPosition, 1, 1);
      }
    `;

    const fragment = `
      #ifdef GL_ES
      precision mediump float;
      #endif

      varying vec2 vUv;
      uniform float rows;

      void main() {
        vec2 st = fract(vUv * rows);
        float d1 = step(st.x, 0.9);
        float d2 = step(0.1, st.y);
        gl_FragColor.rgb = mix(vec3(0.8), vec3(1.0), d1 * d2);
        gl_FragColor.a = 1.0;
      }
    `;

    const canvas = document.querySelector('canvas');
    const renderer = new GlRenderer(canvas);

    // load fragment shader and createProgram
    const program = renderer.compileSync(fragment, vertex);
    renderer.useProgram(program);
    renderer.uniforms.rows = 1;

    const rows = [1, 4, 16, 32, 64];
    let idx = 0;
    const timerId = setInterval(() => {
      renderer.uniforms.rows = rows[idx++];
      if(idx > 4) {
        clearInterval(timerId);
      }
    }, 1000);

    renderer.setMeshData([{
      positions: [
        [-1, -1],
        [-1, 1],
        [1, 1],
        [1, -1],
      ],
      attributes: {
        uv: [
          [0, 0],
          [0, 1],
          [1, 1],
          [1, 0],
        ],
      },
      cells: [[0, 1, 2], [2, 0, 3]],
    }]);

    renderer.render();
  </script>
</body>
</html>